On Tuesday, October 29, 2013 1:02:31 AM UTC, Dave Liquorice wrote:
On Mon, 28 Oct 2013 16:50:16 +0000, The Natural Philosopher wrote:

so it is possible that something has bitched a power line - and quite a
big power line if the station was cut off.

Or breakers in a grid switching center got upset by the surges caused
by lines downstream being brought down and tripped Dungeness off.

Once tripped off and Dungeness going into emergency shutdown it takes
about a week to sort things out and bring it back online.

If the reactor is tripped from full power then if you don't restart within a few hours Xenon135 builds up (it's not produced durectly by the fission reaction, but by decay of Iodine135, so production doesn't stop when fission stops) and absorbs so many neutrons you can't restart safely for several days (I don't have my textbook on reactor physics with me to give more detail...) If you get an unexpected trip it might take too long to assure yourself that it's safe to restart before the deadline.